1. Field of the Invention
The invention relates to an electronically commutated motor (ECM).
2. Description of the Related Art
Conventional permanent-split capacitor (PSC) motors consume a large amount of energy, produce much noise, and have low efficiency. Permanent magnet synchronous motors, such as, e.g., ECM motors, are provided with a motor controller, so that they have high reliability, high controllability, and low noise. It is a trend to substitute an ECM motor for a PSC motor. However, the substitution may result in the following problems:
1) The function of the ECM motor is single and not applicable to different workplaces, for example, operating parameters like the supply voltage cannot be directly set;
2) Conventionally, when an ECM is substituted for a PSC motor, a current sensor is serially connected to the input terminal of the gears; and the gears are in electric connection to one another. When an ECM controlled by a 24 VAC signal is replaced, signal coupling tends to occur, the heating wires tend to malfunction which is a hidden danger;
3) When an ECM controlled by a 24 VAC signal is replaced, the current signal flowing in the current sensor at the input terminal of the motor is weak, and it is difficult to determine whether the gear signals are effective;
4) The state of each gear input line is detected by a current transformer and related circuits, however, the current transformer has a large volume and high product costs and occupies relatively large space of the motor controller, thereby decreasing the heat dissipation of the motor controller; and
5) A plurality of sensing units of the current transformer are embedded in a wiring plug of the motor, the installation of which is difficult, thereby lowering the production efficiency and making large scale production difficult.